The several olfactory cortical areas of the basal forebrain, which receive fibers from the olfactory bulb, provide a relatively simple model for the study of morphological organization of the cerebral cortex. These olfactory areas will be studied in normal and experimental material taken from rat and cat. The structure and afferent connections of these cortical areas in the adult will be analyzed in detail, and correlated with the developeent of these connections and of the laminar organization of the cortex. In these studies several neuroanatomical techniques will be used, including the autoradiographic method of tracing axonal connections, the Golgi method and the electron microscope. Some of these preparations will be quantitatively analyzed by computer-aided image processing. An attempt will be made to demonstrate axonal sprouting in response to partial deafferentation in this site, and to analyze the dependence of such sprouting on the age of the aminal. A study is also being made of the efferent connections of the six constituent nuclei of the amygdala, using the autoradiographic method.